castellations vs. no castellations

Can anyone give me the virtues of SMT package castellations vs. no castellations with particular reference to the ruggedness and reliability of the solder joints? Any references or studies that you can point me to? Also, although I'm in favor of process control instead of inspection, I have been told that X-Ray is the best way to inspect the joints between a PWB and a SMT package with no castellations - True? What brand of X-Ray inspection equipment do you recommend?

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| Can anyone give me the virtues of SMT package castellations vs. no castellations with particular reference to the ruggedness and reliability of the solder joints? Any references or studies that you can point me to? Also, although I'm in favor of process control instead of inspection, I have been told that X-Ray is the best way to inspect the joints between a PWB and a SMT package with no castellations - True? What brand of X-Ray inspection equipment do you recommend? |

Hi Jon!

When I think of castellated components, I think of LCCC's (leadless ceramic chip carriers) or PLCC's without "J-leads", and the susceptability for the solder joints failing unless the substrate material that it is being mounted to has a matching CTE of the device has been well documented...they don't do good on regular FR4 boards and the like. BUT, there are castellated component carriers out there that can provide the needed "Give" or compliance when mounting the device to a substrate that might not have a matching CTE in order to minimise the potential for joint failure, the picture above shows one such carrier. Click on the link below to take you to their page.

Hope this helps...

-Steve Gregory-

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| Can anyone give me the virtues of SMT package castellations vs. no castellations with particular reference to the ruggedness and reliability of the solder joints? Any references or studies that you can point me to? Also, although I'm in favor of process control instead of inspection, I have been told that X-Ray is the best way to inspect the joints between a PWB and a SMT package with no castellations - True? What brand of X-Ray inspection equipment do you recommend? |

If you are talking about LCCC's, little reliability is possible except using particular material types and specific land patterns. Castellations provide more solder joint surface area on the device, obviously, and must be designed not to cause defect at the PCB pad - a long and old story. On similar devices as R/F filter types mounted on carrier PCB's, reliability is not so much an issue as device and mounting substrate TCE's nearly match.

Earl Moon

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